Little brothers are so annoying
by ArtemisApollo97
Summary: This is what happens when your dad turns up unexpectedly with an eight month of child and wants you to look after him for the foreseeable future. Percy Jackson and his twin, my OC, Louisa, are about to find out that little brothers, no matter how cute they are, can be real little devils...
1. Chapter 1

**This is an idea I've had for a while. Tell me what you think PLEASE! :D **

**Just spotted this- 'Valdus' is a boys' name apparently and it means 'powerful'. Does anyone else see how close that is to 'Valdez'? **

**I do not own Percy Jackson and co but Louisa is my OC. Uh… they're roughly eighteen in this, maybe seventeen (and because I'm so nice, Percabeth aren't in Tartarus :) )**

* * *

"I'm bored."

"Again?" Percy looked up at his sister and was momentarily surprised when he saw that she was lying on her back on her bunk with her head a few inches above the floor. "Yeah, I can tell."

There was a knock at the door. Louisa rolled onto her front as Percy got up and answered it.

"Oh, hey Dad."

"Hello, Percy. Hello Louisa."

"Sup." Louisa said, raising a hand in greeting. Poseidon gave a small smile. "Whoa, who's the midget in ya arms?"

"Don't call him that, Lou!" Percy half-scolded, half-laughed.

"Yes… I was wondering if you could look after him for a short while?"

"How long is a short while?" Percy asked.

"How much are we gettin' paid?" Louisa asked at the same time. They both gave her the look, but there was a glimmer of amusement in their eyes. "Sorry for havin' ma priorities straight…"

Percy looked at the tot in his father's arms. He had the same raven hair as Percy and Louisa and was studying Percy with sea green eyes.

"What's his name?"

"Um… Zachary."

"Did you forget his name, Dad?" Percy teased. Poseidon didn't reply, handing Zachary over to Percy. "Hey, you." Percy pulled a face at his new little brother.

"How old is it?"

"He's not an 'it'." Percy said shortly, not looking round.

"Ugh, whatever. How old is whatshisname?" Poseidon pursed his lips. "Dad…" Louisa warned, smirking.

"About six, seven or eight months old."

"Do you even know when he was born?"

"His mother died. I've just got him from an orphanage."

"Oh, OK."

"This ain't gonna cause a World War Three or anythin', is it?" Poseidon sighed.

"No, you two do that on your own."

"Damn right." The twins said proudly, grinning. Poseidon shook his head, smiling. He handed over a baby bag. Louisa took it and nearly dropped it at the unexpected weight of it.

"Bloody hell, how long is it stayin' for?"

"Until I found him a decent family to grow up in." Poseidon replied carefully. He started to glow. "Behave." He told them. They nodded and averted their gaze as he zapped away.

"So, new squirt. Gimme."

"What are you going to do?"

"I'm gonna drown him."

* * *

"Oh, he's so cute." Percy cleared his throat pointedly. "Shut you face, Seaweed Brain." Annabeth said in a merry voice with what appeared to be a genuine smile on her face, but it obviously meant trouble for her boyfriend.

Zachary was sat on Annabeth's bunk, playing with a toy dog the twins had found in the bag Poseidon had given them. It was called 'Doggy' (such an imaginative child).

"Percy didn't let me drown him." Louisa huffed. Annabeth stood up straight and gave her the Look. "Wut? It ain't that bad. He could be like us."

"And if he isn't?" Louisa shrugged.

"Tough."

"You're so heartless." They turned round and saw Leo standing in the doorway. "Found your blueprints." Leo told Annabeth. "Made a few changes."

"You haven't written 'Leo Valdez, your new master' on it, have you?"

"No."

"No, you've written 'Leo Valdez is one with the ladies'."

"No, you said it wrong." Leo ran a hand through his hair, smiling. "Leo Valdez is one with da ladies…"

"Oh gods, you have issues."

"Out!" Louisa shooed him out.

"Definitely one with the ladies." Percy smiled. Leo was dancing around Louisa, purposefully annoying her. He spotted Zachary and changed direction.

"Hi!" He beamed, dropping to his knees in front of the tot. "I'm Leo."

"Eh." Zachary said, holding his toy up.

"Oh, wow. He's so cute." Leo carefully took the dog toy from Zachary and made it dance around the infant as well as making the dog 'talk' in a growly, yet friendly and amusing voice. "You're a lovely owner. Let me give you a nice. Big. Hug." The dog toy gently collided with Zachary and jumped about, making the tot laugh happily. "Can I keep him?"

"No!" Percy laughed.

"Aw, what? Why?"

"He's our brother."

"No way."

"You didn't see the similarities?" Annabeth felt Leo's forehead. "Mmm…" Leo decided to play along.

"How bad is it?"

"Terrible."

"Oh gods, I'm contagious." He jumped up and ran out.

"Stop him!" Annabeth ordered quickly. Louisa ran after Leo before he could start shouting out at the top of his lungs that he was 'contagious'.

"I- ow!" Louisa tackled him and they both went sprawling. Leo tried to scramble up, but she was quicker, tackling him again and sitting on him, Leo lying on his front on the grass. "Well, at least the weather's nice."

"I can change that."

"Please don't. The sun gives me super powers."

"Ya ain't Superman."

"How'd you know?"

"Ya too scrawny."

"Oh, supportive friend of the year much."

* * *

Zachary- now Zach- slept like the dead, which the twins approved of. They had been bickering over who was going to do the night shift during dinner. At least that was one problem resolved.

It turned out Zach was very advanced. The twins woke up to loud crashing and realised Zach had somehow climbed out of the cot that Poseidon had sent and was now running around the cabin, knocking things over and generally making more mess than Percy and Louisa in seconds than they did in a day.

That was something they didn't approve of.

It took ten minutes to catch their brother and another fifteen to get him to sleep. By then, the sun was rising.

Louisa collapsed on her bed and didn't move.

"Lou?"

"Ugh…" She groaned in reply.

"Ditto." Percy said, lying down and attempting to go back to sleep.

They would clean up later. At some point. Later. Much later…

If only they knew how much trouble Zach was going to cause…

* * *

**OK, kind of drabbley, but it's all I've got at the moment. Hopefully I can update again soon! PLEASE REVIEW AND LET ME KNOW WHAT YOU THINK! **


	2. Chapter 2

"Lou, I've been thinking…"

"Never good."

"Thanks for that." Percy sighed. He watched Louisa pour a ton of sugar (not literally) onto her porridge before continuing. "Did Dad seem kind of… shifty to you?"

"That's the sea for ya, bro."

"No, I mean he didn't seem comfortable." Louisa looked at him quizzically. "I dunno… when we asked who the mom was, he seemed annoyed slightly."

"I don't know, bro, I weren't really payin' attention."

"As always."

"So, what then? D'ya think Dad is hidin' somethin'?" Percy shrugged, biting into his bacon sandwich. Zach was sat in a high chair at the head of the table, splashing his spoon in his bowl of mushy cornflakes in milk. Louisa shifted down the bench and eased the spoon from the tot's hold. Zach made to protest, but was interrupted by a mouthful of cornflakes.

Leo dropped down next to Percy, on the opposite side of the table to Louisa.

"Hey." He grinned.

"You've had coffee, haven't you?"

"Only a cup."

"How big was the cup?"

"Uh… not answering that one. How're things with Zach?" Percy told Leo about Zach's trashing adventures the previous night. Leo, obviously, found it highly amusing.

"Oh, that's priceless!"

"If you say so…" Percy sighed, finishing the bacon sandwich.

Chiron trotted over.

"Who's this?"

"New squirt." Louisa replied. Zach threw his bowl on the floor and shook his head, refusing cornflakes. "It's name's Zach 'n' it's a pain in the ass."

"Lou!" Percy scolded lightly. "Honestly…"

"So, Poseidon has claimed him then?"

"Dad bought him straight ta the doorstep 'n' asked for us ta look after him."

"And Lou asked how much we were going to get paid." Leo snickered.

"Aw, Mr. Valdez. I did not know you were another child of Poseidon. Please return to your table."

"See you later, guys." Leo got up and left.

Chiron noticed Zach was staring at him in complete fascination.

"Hello, young Zachary."

"Pony." Zach said, reaching up to the centaur.

"Centaur, my dear boy."

"'Kay." Zach looked at Louisa. "Hung'y." Louisa sighed.

"I hope we're gettin' paid enough…" She grumbled.

* * *

Everyone knew about Zach and he was suddenly very popular. It seemed that the Poseidon twins had finally met their match and that was something they weren't happy about.

"Say 'Percy'." Percy started saying his name slowly. "Per-cy." They were sat at their table, Zach in his highchair while ignoring the mushy cornflakes he had for breakfast.

"Doggy."

"No, Per-cy."

"Doggy." Zach insisted.

"Per-cy."

"Lou!"

"Woo, five bucks ta me!"

"Shut up, Lou." Percy grumbled, taking five bucks from his pocket and reluctantly handing it over to his sister. "Now say 'Percy'." He told Zach. The tot just stared at him blankly.

"Lou." He said simply.

"See, I told ya I was the better twin."

"If you're the _better twin_, you can look after him." Percy got up and started to leave.

"Hell no! Jackson, get ya ass back here!"

"Hell no!" Percy grinned cheekily.

"I will kill you!" Louisa shouted after him. She was in half a mind to go after her brother that second, but Zach was watching her with those big green eyes. Grumbling curses, she sat down heavily. "Stupid brothers…"

* * *

Zach had been around for nearly two weeks. There were more fights than usual between the Poseidon twins over whose turn it was to look after Zach. The infant still wouldn't say 'Percy', but was quite happy chanting his sister's name repeatedly until she eventually got annoyed with him.

Nobody expected what happened next.

Louisa walked into the dining pavilion, looking tired and pale. She was holding Zach at arm's length, but he found it amusing, waving Doggy around.

The daughter of Poseidon marched straight up to the main table where Chiron and Mr. D sat. She sat Zach on the table in front of Chiron, clearly stated, "Have a baby." And then she turned and walked out.

"What have you done?" Chiron smiled down at Zach.

"I scared them." He replied as clear as day. This was an eight month old boy speaking as clearly as someone a year or so older than him. Everyone in the dining pavilion was watching curiously.

"Can I look after him?" Chiron glanced up and saw Leo waving at him.

"If you want." Chiron sighed, studying Zach curiously and cautiously. Zach remained oblivious, mumbling to Doggy. Leo bounced up and grabbed Zach, throwing the infant in the air and making him laugh.

"Zachary, my man." Leo grinned. "You wanna stay with Unki Leo?"

"Yeah!" Zach laughed.

"Excellent. Let's go and blow stuff up."

Leo took care of Zach from then on, with Percy intervening every afternoon, but nobody was sure why Louisa had freaked and dumped her little brother on the table. Percy didn't even know, which confused the lot of them.

"Lou, what happened?" Annabeth asked. Louisa didn't reply, staring out at the sea. She had that look- something was troubling her, but she also seemed uncertain. Annabeth sat properly on the dock next to her friend. "Hellooo, earth to Louisa."

"Huh?"

"Why did you freak?"

"There is somethin' wrong with that kid." Annabeth opened her mouth to retort. "I ain't bein' mean, but he ain't normal, not even for a demigod."

"What'd you mean?"

"Ya know what he said ta me?"

"What?"

"Like, as clear as anythin', the kid just started talkin' 'bout how nice the weather was 'n' said 'Can ya teach me ta play basketball? 'N' can we see Leo later? He's funny'." Annabeth stared at Louisa as if she'd gone crazy. Well, crazier. "I ain't lyin', Annabeth, that kid is whacked."

"Did you tell Chiron?"

"No."

"You should."

"Why's this kid talkin' like that though? It don't make sense." Louisa sighed, running her hands through her hair.

"Are there any crazy demigod ladies in here?"

"Leo, important conversation going on here!" Annabeth called over her shoulder. There was a slight pause.

"Is it a girl thing or can I sit with you?"

"Ugh, yes, you can sit with us." Annabeth shook her head, holding Louisa's gaze like 'can you believe that guy?' Louisa rolled her eyes in response.

Leo sat on the dock behind them, handing Zach to Annabeth.

"Hello you." Annabeth smiled.

"Hi." Zach replied easily. Annabeth felt Louisa's gaze on her, but said nothing.

"I guessed why you freaked, Lou." Leo said, nudging Louisa. "He was sitting there with one of Archimedes' plans in his hands and it looked like he understood."

"Oh no…" Annabeth dumped Zach in Leo's arms, got up and ran out.

"Wh-? Annabeth, don't leave me with this weird kid!" Louisa ran after her. Leo looked at Zach.

"You are seriously strange." Zach just smiled at him.

* * *

**Ooh, what's going on? **

**Although, I'm kinda worried I made it a bit obvious… I don't know… try and guess. **


End file.
